Search

A new type of a positive tone chemically amplified photoresist based on well‐defined, sequence‐controlled polypeptoids with ten repeat‐units are synthesized and their potential for extreme‐UV lithography (EUVL) is demonstrated, resulting in line‐space patterns of 70 nm pitch. The synthesized samples contain 4‐(ethyl) phenol (Eph) and propyne (Ppy) side chains, while their change in solubility upon exposure is induced by the deprotection of 4‐(ethyl) phenol side groups. The resist performance is evaluated using deep UV and extreme‐UV lithography. While all samples are developable in isopropyl alcohol, the content, and the sequence of hydrophobic alkyne side chains lead to a detectable change in solubility, dissolution rate, and resist performance. [ABSTRACT FROM AUTHOR]

The interactions between counterions and electronic carriers in electrically doped semiconducting polymers are important for delocalization of charge carriers, electronic conductivity, and thermal stability. The introduction of a dianions in semiconducting polymers leads to double doping where there is one counterion for two charge carriers. Double doping minimizes structural distortions, but changes the electrostatic interactions between the carriers and counterions. Polymeric ionic liquids (PIL) with croconate dianions are helpful to investigate the role of the counterion in p‐type semiconducting polymers. PILs prevent diffusion of the cation into the semiconducting polymers during ion exchange. The redox‐active croconate dianions undergo ion exchange with doped semiconducting polymers depending on their ionization energy. Croconate dianions are found to reduce doped films of poly(3‐hexyl thiophene), but undergo ion exchange with a polythiophene with tetraethylene glycol side chains, P(g42T‐T), that has a lower ionization energy. The croconate dianion maintains crystalline order in P(g42T‐T) and leads to a lower activation energy for the electrical conductivity than PF6− counterions. The control of the doping level with croconate allows optimization of the thermoelectric performance of the semiconducting polymer. The thermal stability of the doped films of P(g42T‐T) is found to depend strongly on the nature of the counterion. [ABSTRACT FROM AUTHOR]

Block copolymer (BCP) self‐assembly‐assisted doping for semiconductors is used to achieve discrete doping with nanometer‐scale junction depth, high throughput, and large area coverage. As devices become smaller and more sophisticated, spatial control of dopants becomes more critical. A variety of doping methods, such as monolayer doping and δ‐doping, have been developed to replace the conventional doping method, ion‐implantation; however, lateral patterning of dopants relies on photo‐ or e‐beam lithography. To address these challenges, a self‐assembling dopant (boron)‐containing BCP is designed to directly pattern dopants on the nanometer scale. This method skips the lithography step and is compatible with directed self‐assembly approaches. The effect of the boron concentration in the BCP on the doping performance is systematically studied by changing the volume fraction of the boron‐containing block while keeping the domain spacing and the mesoscale morphology constant. Successful self‐assembly of the BCP into a hexagonally packed cylindrical morphology is confirmed by small‐angle X‐ray scattering and resonant soft X‐ray scattering with a 26 nm cylinder‐to‐cylinder distance. Doping silicon using these BCPs enables discrete doped areas with shallow (7–13 nm) junction depth as demonstrated by the depth profile of boron, and supported by a sheet resistance study. [ABSTRACT FROM AUTHOR]

[Display omitted] The polymeric cations of polymeric ionic liquids (PILs) can adsorb from the bulk of a conventional ionic liquid (IL) to the Au(1 1 1) electrode interface and form a boundary layer. The interfacial properties of the PIL boundary layer may be tuned by potential. Atomic force microscopy has been used to investigate the changes of surface morphology, normal and lateral forces of a 5 wt% PIL/IL mixture as a function of potential. Polymeric cations adsorb strongly to Au(1 1 1) and form a polymeric cation-enriched boundary layer at −1.0 V. This boundary layer binds less strongly to the surface at open circuit potential (OCP) and weakly at + 1.0 V. The polymeric cation chains are compressed at −1.0 V and OCP owing to electrical attractions with the electrode surface, but fully stretched at + 1.0 V due to electrical repulsions. The lateral forces of the 5 wt% PIL/IL mixture at −1.0 V and OCP are higher than at + 1.0 V as the polymeric cation-enriched boundary layer is rougher and has stronger interactions with the AFM probe; at + 1.0 V, the lateral force is low and comparable to pure conventional IL due to displacement of polymeric cations with conventional anions in the boundary layer. [ABSTRACT FROM AUTHOR]

In organic mixed ionic–electronic conductors (OMIECs), it is critical to understand the motion of ions in the electrolyte and OMIEC. Generally, the focus is on the movement of net charge during gating, and the motion of neutral anion–cation pairs is seldom considered. Uptake of mobile ion pairs by the semiconductor before electrochemical gating (passive uptake) can be advantageous as this can improve device speed, and both ions can participate in charge compensation during gating. Here, such passive ion pair uptake in high‐speed solid‐state devices is demonstrated using an ion gel electrolyte. This is compared to a polymerized ionic liquid (PIL) electrolyte to understand how ion pair uptake affects device characteristics. Using X‐ray photoelectron spectroscopy, the passive uptake of ion pairs from the ion gel into the OMIEC is detected, whereas no uptake is observed with a PIL electrolyte. This is corroborated by X‐ray scattering, which reveals morphological changes to the OMIEC from the uptake of ion pairs. With in situ Raman, a reorganization of both anions and cations is then observed during gating. Finally, the speed and retention of OMIEC‐based neuromorphic devices are tuned by controlling the freedom of charge motion in the electrolyte. [ABSTRACT FROM AUTHOR]

Polymers that simultaneously transport electrons and ions are paramount to drive the technological advances necessary for next-generation electrochemical devices, including energy storage devices and bioelectronics. However, efforts to describe the motion of ions or electrons separately within polymeric systems become inaccurate when both species are present. Herein, we highlight the basic transport equations necessary to rationalize mixed transport and the multiscale material properties that influence their transport coefficients. Potential figures of merit that enable a suitable performance benchmark in mixed conducting systems independent of end application are discussed. Practical design and implementation of mixed conducting polymers require an understanding of the evolving nature of structure and transport with ionic and electronic carrier density to capture the dynamic disorder inherent in polymeric materials. [ABSTRACT FROM AUTHOR]